Movable tunnel kiln for making clay products and a system with the tunnel kiln

ABSTRACT

The invention relates to a movable tunnel kiln for clay product manufacture and a production process system employing a tunnel kiln. Provided a kiln bottom of the tunnel kiln is fixed and takes a circular shape, the kiln body is circular and movable, road wheels moving on a circular railway are installed on both sides of the kiln body. A circular raw material aging pit concentric with kiln bottom is installed at the site inside the circular kiln bottom, and a complete brickmaking equipment is installed at the central part of the site. An operation mode of stationary bricks stack with movable kiln body is adopted in the invention, which changes the conventional operation of loading and unloading for the brick, and a plurality of cars with auxiliary facilities are cancelled, thereby greatly reduces the kiln construction cost.

FIELD OF THE INVENTION

The invention relates to the field of clay products manufacturingtechnology, is a type of movable tunnel kiln and manufacturingtechnological process system using the tunnel kiln.

BACKGROUND OF THE INVENTION

At present, main equipment for firing clay products like bricks andtiles etc are annular kilns and tunnel kilns. An annular kiln has lowerheat efficiency, a bad working environment, heavy labor intensity and isin major part of manual operation. Therefore, besides some smallbrickfields which are employing annular kilns, most of the large andmedium-sized brickfields adopt tunnel kilns. An existing tunnel kiln hasa tunnel-typed kiln body, its bottom consists of a plurality of kilncars, while the kiln cars with green bricks set on enter one end of thekiln body, pass through the kiln with four zones of preheating, firing,soaking, and cooling, come out from another end of the kiln body. Carpusher, transfer car and drafter etc should be provided. And a number ofauxiliary railways should be paved for returning the cars to the kilnentry. Consequently existing tunnel kilns require pretty largeinvestment, of which one third is for cars. In addition, since the carshas a higher daily maintenance cost for running under a high temperatureenvironment, and air leakage on cars bottom results in quite an amountof heat loss.

SUMMARY OF THE INVENTION

The general object of the invention is aimed at above problem forexisting kilns, to provide a process system of movable tunnel kiln witha higher heat efficiency and a lower construction cost, andmanufacturing clay products using the tunnel kiln.

The main train of thought on realizing the object of the invention is toset the green bricks stationary under the movable kiln body, thus quitea lot of kiln cars might be saved. The specific solution is to provide amovable tunnel kilns comprising a tunnel kiln body and a kiln bottom,said kiln bottom is fixed and takes a circular shape, said kiln body ismovable and circular arc, and is concentric with a circular kiln bottom,road wheels are furnished on both sides of the kiln body, they areplaced on the circular railways on both sides of the kiln bottom, greenbricks to be fired are piled upon a circular kiln bottom, while the kilnbody moves along a circular railway, preheating, firing, soaking, andcooling the green bricks on the kiln bottom subsequently, of which thetechnological process is the same as existing tunnel kiln. After thefired bricks are removed from the kiln bottom, the green bricks are setagain for next firing cycle.

In order to reduce conducting heat loss, lighten the kiln body weight,inner wall of the kiln body in the invention may be piled up withlightweight refractory fibre felt.

On clay products fabrication employing tunnel kiln of the invention,relevant process layout should be adopted, to fully utilize the sitespace inside a circular kiln, shorten the way of material flow, raisethe production efficiency. Its specific process system is as follows:

Install a circular raw material ageing pit concentric with the kilnbottom in the round site space at the inside of aforesaid circular kilnbottom, and a complete brickmaking equipment is set up at the center ofthe above mentioned site space. Clay material, aged material and greenbricks may be delivered with wagons, or transmitted with a conveyor.

On transmitting with a conveyor, may layout according to the followingscheme: a clay material conveyor crossing above the kiln is installedbetween the outside site and inside round site space of kiln bottom, anexit of the clay material conveyor is located at the center of aforesaidinside site space of the kiln bottom, a raw material conveyor, whichleads to aforesaid ageing pit and perform circular motion along theageing pit is installed under the clay material conveyor. An ageingmaterial conveyor which performs circular motion along the ageing pit isinstalled between the ageing pit and the brickmaking equipment. Amovable trestle crosses above the ageing pit. Clay material coming fromoutside of kiln bottom enter the ageing pit by aforesaid clay materialconveyor, then is aged and delivered to the brickmaking equipment at thecenter of the site with an aged material conveyor, green bricks aredelivered to be stacked via a trestle at the kiln bottom preparing fornext firing.

Ageing pit of the invention is designed to be circular, a conveyormoving along the ageing pit and a clay material conveyor are provided,on one end the aged material may be taken out successively along thecircular ageing pit and new clay raw material may be supplied, enablingthe ageing treatment to be performed in continuous circulations on theother end the site space may also be fully utilized. Above mentionedconveyor exit is the feeding end for ageing pit, and the entry forageing material conveyor is the exit of ageing pit.

Because the operation mode of stationary green bricks stack and amovable kiln body moving along a circular railway is employed in presentinvention, so that conventional loading and unloading operation, aplurality of kiln cars and auxiliary devices for existing tunnel kilnsare canceled, which not only greatly reduces kiln construction andmaintenance costs, but also saves labor, Improves working conditions,and is suitable for mechanical operation. Since the kiln cars andauxiliary facilities have been cancelled, therefore not only greatlyreduce the fault rate but also eliminate heat loss resulted from airleakage on the kiln cars bottom in existing tunnel kiln, and heatefficiency will be raised. Moreover, since the green bricks stack arestationary in the firing process, therefore the damage ratio is lower.The manufacturing process system matching with tunnel kilns of presentinvention not only shorts the material flow process, but alsoeffectively utilizes the site space, thereby raises the over allproduction efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

By referring to the accompanying drawing, as follows the foregoing andimportant objects of the present invention shall be described in detail.

FIG. 1 is a is a schematic diagram of overall process system in presentinvention.

FIG. 2 is a sectional view taken along line A--A in FIG. 1.

FIG. 3 is a structural diagram of a kiln wall in present invention.

FIG. 4 is another structural diagram of a kiln wall in presentinvention.

FIG. 5 is a structural diagram of a road wheel in present invention.

FIG. 6 is a top view of FIG. 5.

FIG. 7 is a sketch of the first example of a kiln wall in presentinvention.

FIG. 8 is a exploded view of the second example of a kiln wall inpresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in FIG. 1, FIG. 2, kiln bottom 1 is circular, paved byrefractory plates. A circular railway 2 with a triangular cross sectionis installed between inside and outside of the kiln bottom. Kiln body 3takes the shape of a circular arc. The road wheel 29 of which are movingon a railway in both sides, therefore kiln body 3 is movable alongrailway 2. In order to fully utilize the site space surrounded by theinside of kiln bottom 1, the brickmaking equipment 6 and its auxiliaryfacilities etc are installed in the central area of site space, acircular ageing pit 7 is set upon the periphery of the central area, andthe ageing pit is concentric with kiln bottom 1. Productive process ofclay products is that firstly, the clay material should be aged, thendelivered to the brickmaking equipment for green bricks production,after the green bricks are dried they are send to the kiln for firing.Since the kiln bottom of tunnel kilns is a sealed circular, thereforetransport devices are required between clay material and ageing pit, andamong ageing pit, the brickmaking equipment and tunnel kiln. To thisend, a fixed clay material conveyor 8 is erected between the inside andoutside of kiln bottom 1 crossing above the kiln, and its exit 9 islocated at the center of site space 5. A conveyor 10 leading to ageingpit 7 is installed under conveyor 8, and feeding bin 11 of conveyor 10is directed to the exit 9 of conveyor 8. Therefore, clay material canfall into ageing pit 7 via conveyor 8 and 10.

Exit 12 of conveyor 10 is a free end, its feeding end (i.e. bin 11) isarticulated on pivot 51, so that the conveyor 10 may revolve aroundpivot 51, supplying raw material for the vacant zone of circular ageingpit. An aged material conveyor 13 is also installed between ageing pit 7and brickmaking equipment 6, its exit is articulated on another centralpivot 52, therefore the feeding end of aged material conveyor 13 is alsomovable along the ageing pit to take out aged material successively anddeliver to the brickmaking equipment. Movable trestle 15 acrosses avacant zone 14 of ageing pit between conveyor 10 and conveyor 13, toserve as green bricks transport device between the kiln bottom.

As shown in FIG. 3, FIG. 4, inner wall of kiln body 16 consists ofrefractory fibre felted laminate 17 mounted on frame 20, fireproofcoating laminate 18 located on inside face of refractory fibre feltedlaminate and the cement plaster cladding material 19 located on outsideface of the refractory fibre felted laminate. In which frame 20 consistsof a longitudinal lacing wire 21 passing through refractory fibre feltedlaminate, a zigzag lateral lacing wire 22 connected with longitudinallacing wire 21 and an outer layer steel wire gauze 23. On fabrication,refractory fibre felt (one or several laminates) and zigzag laterallacing wire 22 are stacked in separation, then pass through therefractory fibre felt and lateral lacing wire with longitudinal lacingwire 21, and they are firmly clamped by screw bolts to form a wall.Coating laminate 18 is fabricated as follows: first squeezes therefractory mud into the surface layer of refractory fibre felt by a highpressure mud pump to form a fully squeezed laminate with a definitethickness, then coats a laminate of refractory mud to enhance the airtightness of inner wall. Since above kiln wall structure has beenadopted, therefore the kiln body may be built in section in a factory,then splice a kiln body with the required length on site according todemand. The numerals in the diagram are: 53--coal hole, 24--sandwichspace, serving as a heat transfer channel or flue channel, 25--outerwall, 26--sand seal plate, 27--sand seal trough.

A single layer inner wall structure is shown in FIG. 4, sandwich space24 is located between outer and inner walls. FIG. 3 illustrates anotherstructure form of skin wall, in which both the outer wall 54 and innerwall 55 adopt the inner wall structure form of FIG. 3, other structureare the same as FIG. 4.

Outrigger 28 installed with road wheel 29 is mounted on side of abovekiln body, moreover it is fastened on frame 20 of outer and inner walls.Since the kiln body is longer, and moves under thermal condition, if theroad wheels are rigidly connected with the kiln body, thus when a railposition deviates, or a foreign matter exists on the rails, or kiln bodydeformation etc occurred, derailing of road wheels may take place. Inorder to avoid such a condition, wheel carriers of the road wheels areflexibly connected with the kiln body. One of the specific examples isshown in FIG. 3, FIG. 5, FIG. 6. Every two road wheels 29 constitute agroup, which is mounted on wheel carrier 30, a rubber rod 31 isinstalled at the center of wheel carrier, longitudinal part 32 of kilnbody outrigger 28 is placed on the rubber rod, i.e, weight of the kilnbody is supported by the wheel carriers of road wheels. In this way, tworoad wheel in each group may swing up and down with the rubber rod as apivot point, moreover the rubber rod may perform flexibly bending onforcing, not only avoid derailing, but also realize buffering.

In the second setting and firing process, tunnel kiln chamber isgenerally divided into four zones of preheating, firing, soaking, andcooling. Kiln chamber layout of second setting and firing tunnel kiln inpresent invention is also the same. FIG. 7 is a simple schematic ofsecond setting and firing tunnel kiln in present invention. A kiln doorriser 33 is installed at the feeding end of the kiln, it consists offlash board 34 and flash board guide way 35. Flue holes 36 inter linkwith exhaust fan 38 on the kiln roof via flue channel 37 in the kiln toexhaust the flue gas in kiln.

FIG. 8 shows a structure of once-setting-firing tunnel kiln. It is thesame as existing tunnel kiln. The kiln body is elongated, and a dryingzone 50 is added. Air heat transfer channel 39 of the kiln in thisembodiment is inter linked with the chamber of low, medium temperaturedrying zone of the kiln via exhaust fan 40 and inner wall channel 41 ofkiln drying zone. Chamber flue holes 42 of kiln preheating zone areinterlinked with a chamber of high temperature drying zone via anotherexhaust fan 43 and another inner kiln channel 44, i.e. air in lowertemperature coming from above air heat transfer channel 39 enters thelow, medium temperature drying zone. Smoke gas in higher temperaturecoming from preheating zone enters the high temperature drying zone,drys the green bricks gradually from low temperature to hightemperature, thereby not only ensures drying quality, but also avoidscracking or deformation of green bricks. Numerals in the diagram are:46--air entry of low temperature drying zone, 47--air entry of mediumtemperature drying zone, 48--air entry of high temperature drying zone,49--exhaust fan of the kiln roof.

What is claimed is:
 1. A tunnel kiln comprising:a circular kiln bottom;a pair of circular railways installed on both sides of the circular kilnbottom; a movable tunnel kiln body; road wheels connected to the movablekiln body, the road wheels being rotatably engaged with the pair ofrailways so that the movable tunnel kiln body can move along thecircular railways; a circular raw material aging pit concentric with thekiln bottom inside a round site space at the inside of the circular kilnbottom upon the periphery of the central area of the round site space;and complete brickmaking equipment at a center of said round site space.2. A tunnel kiln as defined in claim 1, wherein an inner wall of thekiln body is piled up with lightweight refractory fiber feltedlaminates.
 3. A tunnel kiln as defined in claim 2, wherein an inner kilnwall of the movable tunnel kiln body comprises:a frame comprising asteel wire gauze, a longitudinal lacing wire, and a zigzag laterallacing wire connected with longitudinal lacing wire; a refractory fiberfelted laminate mounted on the frame such that the longitudinal lacingwire and the zigzag lateral lacing wire pass through the refractoryfiber felted laminate, the refractory fiber felted laminate being formedon one side of the steel wire gauze; a fire-proof coating laminateformed on the refractory fiber felted laminate; and a cement plastercladding material laminate on the other side of the steel wire gauze. 4.A tunnel kiln as defined in claim 3, wherein the road wheels areconnected to the kiln body via a wheel carrier which is detachablyinstalled to the kiln body.
 5. A tunnel kiln as defined in claim 4,wherein two road wheels are mounted on the wheel carrier and a rubberrod is installed on the center of the wheel carrier, and wherein anoutrigger part of the kiln body outrigger is placed on rubber rod.
 6. Atunnel kiln as defined in claim 10, further comprising:a clay materialconveyor installed between the inside and the outside of the kiln bottomcrossing over the kiln body, the clay material conveyor conveying claymaterial between the round site space defined by the circular kilnbottom and an outside of the circular kiln bottom, an exit of theconveyor being located at a bin above the center of the round sitespace, a raw material conveyor installed under the clay materialconveyor and at the center of the round site space between the exit ofconveyor and the aging pit at the periphery of the central area of theround site space to receive the clay material exiting from the bin abovethe center of the round site space and transferring it to the aging pitupon the periphery of the central area of the round site space, anaging-pit end of the raw material conveyor being circularly movablealong the aging pit; an aged material conveyor installed between theaging pit and the brickmaking equipment at the center of the round sitespace to transfer aged material from the aging pit to the brickmakingequipment, an aging-pit end of the aged material conveyor beingcircularly movable along the aging pit; and a movable trestle installedabove the aging pit, the trestle crossing beyond aging pit.
 7. A tunnelkiln as defined in claim 1, wherein an air heat transfer channel of thekiln body leads to a first exhaust fan which leads to a first inner wallchannel of the drying zone in the kiln body while chamber flue holes ofa preheating zone in the kiln body lead to a second exhaust fan whichleads to a second inner channel of the kiln body such that air of lowertemperature coming from said air heat transfer channel of the kiln bodyenters through said first exhaust fan and on into said first inner wallchannel of the drying zone and said preheating zone provides smoke inhigher temperature which enters said second inner channel of the kilnbody through said second exhaust fan.